Method of manufacturing a composite rim

ABSTRACT

A method of manufacturing a composite rim includes following steps of: disposing a composite material on an outer surface of an air bag to form a semi-formed rim, wherein the air bag is a completely closed annular tube without any through opening on the outer surface and contains a thermal expansion material thereinside; disposing the semi-formed rim in a mold; and heating the thermal expansion material so that the thermal expansion material expands and inflates the air bag and the semi-formed rim is then solidified.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a method of manufacturing a compositerim.

Description of the Prior Art

A conventional method of manufacturing a composite rim process, such asthe traditional internal pressure process, needs to place nylon, latexor silicone air bag in the pre-preg composite material (such as carbonfiber). An air blowing port must be provided on the air bag forinflating the air bag during heating and solidifying the resin of thecomposite, so that there is a pressure different between inside andoutside of the air bag for squeezing out excess resin and push thepre-preg composite toward the mold to enhance combination of layers ofthe pre-preg composite. During the solidification process, the airpressure needs to be controlled within a reasonable range of pressuredifferent between inside and outside of the air bag. With an airpressure too low, the resin content of the final product will be toohigh, the bonding density between layers of the pre-preg composite willbe lowered, reducing the structural strength and performance; while withan air pressure too high, the resin content of the final product will betoo low, which will cause a decrease in strength and performance of thefinal product.

The shortcoming of the conventional method of manufacturing a compositerim process is that it requires manual work to additionally dispose theblowing port to the air bag, and the yield rate depends on theexperience and skill of the personnel. If there is any flaw in theprocess of mounting the blowing port, it may cause insufficient airpressure for blowing the air bag or may cause the product to be scrappeddue to air leakage.

The present invention is, therefore, arisen to obviate or at leastmitigate the above-mentioned disadvantages.

SUMMARY OF THE INVENTION

The main object of the present invention is to provide a method ofmanufacturing a composite rim which has high precision, good yield andhigh structural strength.

To achieve the above and other objects, a method of manufacturing acomposite rim is provided, including steps of: disposing a compositematerial on an outer surface of an air bag to form a semi-formed rim,wherein the air bag is a completely closed annular tube without anythrough opening on the outer surface and contains a thermal expansionmaterial thereinside; disposing the semi-formed rim in a mold; andheating the thermal expansion material so that the thermal expansionmaterial expands and inflates the air bag and the semi-formed rim isthen solidified.

The present invention will become more obvious from the followingdescription when taken in connection with the accompanying drawings,which show, for purpose of illustrations only, the preferredembodiment(s) in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing showing a closed air bag containing a thermalexpansion material according to a preferable embodiment of the presentinvention;

FIG. 2 is a drawing showing an annular thermal expansion materialaccording to a preferable embodiment of the present invention;

FIGS. 3 and 4 are drawings showing a thermal expansion materialinflating an air bag according to a preferable embodiment of the presentinvention;

FIGS. 5 and 6 are drawings showing a semi-formed rim formed in a moldaccording to a preferable embodiment of the present invention;

FIG. 7 is a drawing showing forming a tire installation groove accordingto a preferable embodiment of the present invention;

FIGS. 8 and 9 are drawings showing a composite rim with an air bagremoved according to a preferable embodiment of the present invention;and

FIGS. 10 and 11 are drawings showing a thermal expansion materialinflating an air bag according to another preferable embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 1 to 9 for a preferable embodiment of the presentinvention. A method of manufacturing a composite rim of the presentinvention includes the following steps of: disposing a compositematerial 10 on an outer surface of an air bag 20 to form a semi-formedrim 30, wherein the air bag 20 is a completely closed annular tubewithout any through opening on the outer surface and contains a thermalexpansion material 40 thereinside; disposing the semi-formed rim 30 in amold 50; heating the thermal expansion material 40 so that the thermalexpansion material 40 expands and inflates the air bag 20 and thesemi-formed rim 30 is solidified. Whereby, it has high precision andgood yield, and the air bag 20 can be well fitted with the compositematerial 10, which provides high structural strength of the compositerim.

The composite material 10 is a carbon fiber composite material; however,the composite material may be other type of reinforced fiber compositematerial. In this embodiment, the thermal expansion material 40 is wax,and the air bag 20 is inflated by the thermal expansion material 40 of avolume change of 15%. Preferably, after the semi-formed rim 30 issolidified, the air bag 20 and the thermal expansion material 40 areremoved (FIG. 9). In this embodiment, after the semi-formed rim 30 issolidified, an outer annular part of the semi-formed rim 30 may beremoved to form a tire installation groove 31 for receiving a tire.

In an alternative embodiment shown in FIGS. 10 and 11, the thermalexpansion material 40 a produces gas 41 during inflation of the air bag20. The pressure generated by the thermal expansion material 40 a toinflate the air bag 20 is 1 kg/cm² to 20 kg/cm². The thermal expansionmaterial 40 a may be ammonium carbonate. After the inflation of thethermal expansion material 40, the air bag 20 contains a part of thethermal expansion material 40 a which is solid state and the gas 41which is produced from thermal expansion material 40. It is noted thatthe thermal expansion material 40 a may be completely gasified, and noneof residue of solid-state thermal expansion material is contained in theair bag 20. In the embodiment with the thermal expansion material 40 abeing ammonium carbonate, the ammonium carbonate can be decomposed intocarbon dioxide, ammonia and H₂O at a temperature about 60□, wherein 1gram of ammonium carbonate can be decomposed to produce 0.25 grams ofcarbon dioxide which is equal to 0.5 liters of gas. The amount of addingammonium carbonate can be chosen according to the reserved space of themold 50 and predetermined inflation rate.

It is noted that the thermal expansion material in the air bag,initially, may be gas such as inert gas, in which gas can have greatervolume change when heated, and inert gas is much stable and safe;however, other gas may be applicable. The thermal expansion material inthe air bag, initially, may be fluid, which can provide preciseinflation, sufficient inflation volume change and good inflation rate.Gas-state or fluid-state thermal expansion material is convenient to beremoved after the semi-formed rim is solidified.

Although particular embodiments of the invention have been described indetail for purposes of illustration, various modifications andenhancements may be made without departing from the spirit and scope ofthe invention. Accordingly, the invention is not to be limited except asby the appended claims.

What is claimed is:
 1. A method of manufacturing a composite rim,including steps of: disposing a composite material on an outer surfaceof an air bag to form a semi-formed rim, wherein the air bag is acompletely closed annular tube without any through opening on the outersurface and contains a thermal expansion material thereinside; disposingthe semi-formed rim in a mold; and heating the thermal expansionmaterial so that the thermal expansion material expands and inflates theair bag and the semi-formed rim is then solidified.
 2. The method ofclaim 1, wherein the composite material is a carbon fiber compositematerial.
 3. The method of claim 1, wherein the pressure generated bythe thermal expansion material to inflate the air bag is 1 kg/cm² to 20kg/cm^(2.)
 4. The method of claim 3, wherein the thermal expansionmaterial produces gas during inflation of the air bag.
 5. The method ofclaim 4, wherein the thermal expansion material is ammonium carbonate.6. The method of claim 5, wherein the composite material is a carbonfiber composite material; after the inflation of the thermal expansionmaterial, the air bag contains a part of the thermal expansion materialwhich is solid state and the gas which is produced from the thermalexpansion material; after the semi-formed rim is solidified, the air bagand the thermal expansion material are removed.
 7. The method of claim1, wherein the air bag is inflated by the thermal expansion material ofa volume change of 15%.
 8. The method of claim 7, wherein the thermalexpansion material is wax.
 9. The method of claim 8, wherein thecomposite material is carbon fiber composite material; after thesemi-formed rim is solidified, the air bag and the thermal expansionmaterial are removed.
 10. The method of claim 1, wherein the thermalexpansion material is gas.